Scroll compressor

ABSTRACT

A scroll compressor includes a rotation shaft; a first scroll and a second scroll engaged with the first scroll to form a compression chamber between the second scroll and the first scroll. The second scroll includes a key recess. The scroll compressor includes an Oldham ring having a ring portion and a key portion protruding toward the key recess, from the ring portion. The key portion is coupled to the key recess in a sliding manner such that the second scroll orbits with respect to the first scroll. The scroll compressor also includes a wear preventing member installed between the key recess and the key portion. The second scroll includes an axial direction separation prevention groove formed by recessing one surface off the key recess. The wear preventing member includes an axial direction separation prevention portion held in place by the axial direction separation prevention groove.

CROSS-REFERENCE TO RELATED APPLICATION

Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of earlier filing date and right of priority to Korean Application No. 10-2018-0053335, filed on May 9, 2018, and Korean Application No. 10-2018-0103847, filed on Aug. 31, 2018, the contents of both of which are incorporated by reference herein in their entireties.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

The present disclosure relates to a compressor and particularly to a scroll compressor.

2. Background of the Related Art

In a scroll type compressor, a motor part formed as a rotary motor is installed inside a closed casing, a compression unit including a fixed scroll and an orbiting scroll is installed on one side of the motor part, and the motor part and the compression part are connected by a rotating shaft so that a rotational force of the motor part is transmitted to the compression unit. The rotational force transmitted to the compression unit causes the orbiting scroll to perform an orbiting movement with respect to the fixed scroll to form a pair of two compression chambers including a suction chamber, an intermediate compression chamber and a discharge chamber, so that a refrigerant is sucked into both compression chambers and compressed and simultaneously discharged.

Such a scroll-type compressor is provided with a rotation preventing mechanism for preventing rotation of the orbiting scroll. As the rotation preventing mechanism, an Oldham ring or a pin-and-ring may be applied.

The pin-and-ring type is advantageous compared with the above-mentioned

Oldham ring type in that reliability is improved due to enhancement of durability of the rotation preventing mechanism and an increase in weight of the compressor due to the rotation preventing mechanism is suppressed. Meanwhile, the pin-and-ring type is relatively disadvantageous in terms of assembly since a plurality of pins and rings must be installed in each of the orbiting scroll and a member in contacting therewith.

Therefore, research has been continuing to replace the pin-and-ring type by improving a material of the Oldham ring.

Particularly, when the scroll compressor is applied to an automotive air conditioning system, the Oldham ring may be formed of aluminum material in consideration of the weight and workability of the compressor. When aluminum is applied to the Oldham ring, the weight of the Oldham ring may be lowered and workability and productivity may be improved.

However, when the weight of the compressor is considered, it is advantageous to manufacture the peripheral orbiting scroll, a main frame, or the fixed scroll, as well as the Oldham ring, using the same material, and in this case, since the material of the Oldham ring and a material of a relative frictional surface are the same, friction characteristics are significantly degraded. Recently, a technique for improving wear reliability of a key portion of the Oldham ring has been introduced.

Among Prior Art documents, Prior Art 1 (US 2017-0234313 A) is a technique for increasing wear resistance, while reducing the weight of the Oldham ring by forming a ring portion and a key portion of the Oldham ring with different materials. Prior Art 2 (KR 10-1997-0021751) is a technique for surface-treating the Oldham ring to suppress the Oldham ring from being welded to the orbiting scroll or the fixed scroll.

However, in the conventional scroll compressor as described above, when the ring portion and the key portion of the Oldham ring are made of different materials, a manufacturing process of pre-producing and post-assembling the ring portion and the key portion may be complicated. Also, in this case, a sectional area of a portion where the ring portion and the key portion are assembled may be reduced, so that a bearing strength against the key portion is weakened, and reliability with respect to the bearing may be lowered. Also, in this case, a gap is generated at a joint portion of the ring portion and the key portion due to a machining error or an assembly error between the ring portion and the key portion, and when the compressor is driven, the key portion is warped relative to the ring portion so that the orbiting scroll is pushed in a circumferential direction, resultantly forming a gap between the wraps to increase compression loss. Also, coefficients of thermal expansion of the ring portion and the key portion are different from each other, resulting in separation of the key portion from the ring portion or idling.

In the conventional scroll compressor, a coating layer may be formed on a surface of the Oldham ring with a lubricating material or the like. However, manufacturing cost is increased due to formation of a separate coating layer, and the coating layer is peeled off or worn when it is used for a long time to damage the Oldham ring or increase friction loss.

SUMMARY OF THE DISCLOSURE

Therefore, an aspect of the detailed description is to provide a scroll compressor having an overall weight reduced by reducing a weight of an Oldham ring, when the Oldham ring is applied.

Further, another aspect of the detailed description is to provide a scroll compressor in which an Oldham ring is formed of the same material as that of a frame to which the Oldham ring is coupled, an orbiting scroll, or a fixed scroll.

Further, another aspect of the detailed description is to provide a scroll compressor in which both members to which an Oldham ring is coupled are formed of the same material and the Oldham ring is formed of the same material as that of the both members to which the Oldham ring is coupled. Here, the both members may refer to A member coupled to one side of the Oldham ring and B member coupled to another side of the Oldham ring.

Further, another aspect of the detailed description is to provide a scroll compressor in which a ring portion and a key portion forming an Oldham ring are formed of the same material.

Further, another aspect of the detailed description is to provide a scroll compressor capable of enhancing workability and productivity for an Oldham ring.

Further, another aspect of the detailed description is to provide a scroll compressor in which generation of a gap of an allowable value or greater between a key portion of an Oldham ring and a key recess of a frame, an orbiting scroll, or a fixed scroll to which the key portion is coupled is suppressed to increase compressor efficiency.

Further, another aspect of the detailed description is to provide a scroll compressor capable of securing a bearing strength of a key portion with respect to a ring portion forming an Oldham ring, thereby enhancing reliability.

Further, another aspect of the detailed description is to provide a scroll compressor capable of suppressing idling of a key portion with respect to a ring portion forming an Oldham ring, thereby enhancing reliability.

Further, another aspect of the detailed description is to provide a scroll compressor in which a ring portion and a key portion forming an Oldham ring are formed as a single body.

Another aspect of the detailed description is to provide a scroll compressor that has a structure that prevents an Oldham ring from being separated from an installation position along an axial direction of a rotation shaft and a radial direction of the rotation shaft.

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, a scroll compressor includes: a first scroll; a second scroll engaged with the first scroll and performing an orbiting movement; and an Oldham ring including a ring portion formed in a ring shape and a key portion protruding from the ring portion, wherein the key portion is slidably coupled to a key recess provided in the second scroll to enable the second scroll to perform an orbiting movement with respect to the first scroll, wherein the key portion of the Oldham ring is formed of the same material as the second scroll.

Here, a wear preventing member formed of a material different from the second scroll or the Oldham ring may be provided between the key portion and the key recess.

The wear preventing member may be inserted into the key recess so as to be coupled.

An escape preventing portion for preventing the wear preventing member from escaping may be formed between the wear preventing member and a member to which the wear preventing member is coupled.

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, a scroll compressor includes: a first scroll; a second scroll engaged with the first scroll to perform an orbiting movement to form a compression chamber with the first scroll; and an Oldham ring including a ring portion formed in a ring shape and a key portion protruding from the ring portion, wherein the key portion is slidably coupled to a key recess provided in the second scroll to enable the second scroll to perform an orbiting movement with respect to the first scroll, wherein a wear preventing member is provided between the key recess of the second scroll and the key portion of the Oldham ring.

Here, the key portion of the Oldham ring may be formed of the same material as the second scroll, and the wear preventing member may be formed of a material different from the key recess of the second scroll or the key portion of the Oldham ring.

The key portion and the ring portion of the Oldham ring may be formed of the same material.

The key portion and the ring portion of the Oldham ring may be formed as a single body.

The wear preventing member may include a first reinforcement surface and a second reinforcement surface arranged in parallel in a radial direction and a connection surface connecting the first reinforcement surface and the second reinforcement surface, and the connection surface extends from one ends of the first reinforcement surface and the second reinforcement surface facing each other in the radial direction to connect the first reinforcement surface and the second reinforcement surface.

The connection surface may be formed to expand in a circumferential direction, relative to an interval between the first reinforcement surface and the second reinforcement surface, and an escape preventing recess into which the connection surface is inserted to support the wear preventing member in the radial direction may be formed at one end of the key recess.

Here, the connection surface may have the same diameter as the interval between the first reinforcement surface and the second reinforcement surface, and a fixing pin may be coupled to one end of the key recess to support the connection surface in the radial direction.

Here, the connection surface may have the same diameter as the interval between the first reinforcement surface and the second reinforcement surface, and an escape preventing recess into which one axial end of the wear preventing member is inserted and supported may be formed in the key recess.

Here, the wear preventing member may include a first reinforcement surface and a second reinforcement surface arranged in parallel in a radial direction and a third reinforcement surface extending from one axial ends where the first reinforcement surface and the second reinforcement surface face each other in a circumferential direction to connect the first reinforcement surface and the second reinforcement surface.

Escape preventing surfaces may be further formed on the first reinforcement surface and the second reinforcement surface and extend from one facing ends of the first reinforcement surface and the second reinforcement surface to support the wear preventing member in the radial direction, and an escape preventing recess may be formed at one end of the key recess and expand, relative to a width of the key recess, in the circumferential direction, into which the escape preventing surface is inserted.

Here, an oil storage recess may be formed to be deeper than a bottom surface of the key recess in the second scroll, and the oil storage recess may be formed to communicate with the key recess outside a movement range of the key portion.

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, a scroll compressor includes: a casing; a driving motor in which a stator is fixed to an inner space of the casing and a rotor is rotatably provided in the stator; a first scroll provided on one side of the driving motor; a second scroll engaged with the first scroll to form a compression chamber with the first scroll, while performing an orbiting movement, and having a plurality of first key recesses; a rotating shaft in which one end is coupled to the rotor of the driving motor and the other end is eccentrically coupled to the second scroll so as to overlap with the compression chamber in a radial direction; a frame provided on the opposite side of the first scroll with the second scroll interposed therebetween and having a plurality of second key recesses; an Oldham ring having a ring portion located between the frame and the second scroll and a plurality of key portions protruding from the ring portion and slidably inserted into the first key recess and the second key recess; and a wear preventing member formed of a material different from the Oldham ring or the second scroll and provided between the first key recess or the second key recess and the key portion of the Oldham ring inserted therein.

Here, the Oldham ring may be formed of the same material as the second scroll or the frame.

The ring portion and the key portion of the Oldham ring may be formed of the same material and formed as a single body.

The wear preventing member may be inserted into the first key recess or the second key recess and an escape preventing portion may be provided between the first key recess or the second key recess and the wear preventing member inserted therein to suppress escaping of the wear preventing member from the key recess in the radial direction.

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, there is provided a scroll compressor including an axial direction separation prevention groove that prevents a wear preventing member from being separated in an axial direction; and an axial direction separation prevention portion.

According to an aspect of the present disclosure, there is provided a scroll compressor including: a rotation shaft; a first scroll that is provided on one side of the rotation shaft; a second scroll that is engaged with the first scroll to form a compression chamber between the second scroll and the first scroll, and that includes a key recess in a surface that is opposite in direction to a surface that faces the first scroll; a Oldham ring that includes a ring portion in the shape of a circle and a key portion that protrudes, toward the key recess, from the ring portion to be coupled to the key recess in a sliding manner, and is formed to cause the second scroll to orbit with respect to the first scroll.; and a wear preventing member that is installed between the key recess in the second scroll and the key portion of the Oldham ring.

In the scroll compressor, the second scroll may include an axial direction separation prevention groove that is formed as a result of recessing one surface of the key recess.

In the scroll compressor, the wear preventing member may include an axial direction separation prevention portion that reaches stably into the axial direction separation prevention groove and is held in place by a circumference of the axial direction separation prevention groove, in order to prevent separation from the key recess along an axial direction of the rotation.

In the scroll compressor, the Oldham ring may be formed of the same material as the second scroll, and the wear preventing member may be formed of material that is different from that of the key recess in the second scroll or the key portion of the Oldham ring.

In the scroll compressor, the ring portion and the key portion may be formed of the same material.

In the scroll compressor, the ring portion and the key portion may be formed into a single body.

In the scroll compressor, the wear preventing member may further include first and second reinforcement plates that extend in parallel to each other along a radial direction of the rotation shaft, from positions that are at some distance away from each other, and radial direction separation prevention portions that protrude from one end of the first reinforcement plate and one end of the second reinforcement plate, which face each other, respectively, in order to prevent the wear preventing member from being separated from the key recess along the radial direction of the rotation shaft.

In the scroll compressor, the radial direction separation prevention portions may be positioned closer to the rotation shaft than the first reinforcement plate or the second reinforcement plate.

In the scroll compressor, each of the first reinforcement plate and the second reinforcement plate may include a fixation end that is connected to the radial direction separation prevention portion, and a free end that is formed in a direction opposite a direction of the fixation end, and the axial direction separation prevention portions may be formed to extend from the free end of the first reinforcement plate and the free end of the second reinforcement plate, respectively, in a direction away from each other.

In the scroll compressor, the second scroll may further include a first side wall in the key recess, which is formed to be kept in close contact with the first reinforcement plate, a second side wall in the key recess, which is formed to be kept in close contact with the second reinforcement plate, and faces the first side wall, from a position that is at some distance away from the first side wall, and a bottom surface in the key recess, which is formed to connect the first side wall and the second wall to each other along a circumferential direction of the rotation shaft, and faces the key portion, and the axial direction separation prevention groove may be formed in the shape of a chamfer shape on a border between an edge of the second scroll and the first side wall, and on a border of an edge of the second scroll and the second side wall.

In the scroll compressor, the axial direction separation prevention portion may be formed as a result of partially cutting the free end of the first reinforcement plate and the second reinforcement plate in the radial direction of the rotation shaft.

In the scroll compressor, each of the free end of the first reinforcement plate and the free end of the second reinforcement plate may include a first part that extends along a direction of extension of the first reinforcement plate and the second reinforcement plate, and a second part that is cut off and extends from the first part to form the axial direction separation prevention portion, and the second part may be closer to a bottom surface of the key recess than the first part.

In the scroll compressor, the second scroll may further include a first side wall in the key recess, which is formed to be kept in close contact with the first reinforcement plate, a second side wall in the key recess, which is formed to be kept in close contact with the second reinforcement plate, and faces the first side wall, from a position that is at some distance away from the first side wall, and a bottom surface in the key recess, which is formed to connect the first side wall and the second wall to each other and faces the key portion, each of the first side wall and the second side wall may be divided into a first part that is relatively remote, along the axial direction of the rotation shaft, from the bottom surface of the key recess, and a second part that is relatively close to the bottom surface of the key recess, and the axial direction separation prevention groove may be formed in the shape of a chamfer on a border between an edge of the second scroll and the second part.

In the scroll compressor, the radial direction separation prevention portion may be connected to one end of the first reinforcement plate and one end of the second reinforcement plate to have a curved surface with an arcuate cross section, and a diameter of a circle that corresponds to the circular arc may be greater than a distance between the first reinforcement plate and the second reinforcement plate.

In the scroll compressor, and a magnitude of a central angle of the circular arc may be greater than 90°.

In the scroll compressor, the second scroll may include a radial direction separation prevention groove that is formed in the key recess, and the radial direction separation prevention groove may have a circular segment that corresponds to the circular arc to accommodate the radial direction separation prevention portion.

In the scroll compressor, the radial direction separation prevention groove may be formed at a closer position to the rotation shaft than the radial direction separation prevention groove or the key recess.

In the scroll compressor, the axial direction separation prevention groove may be formed as a result of recessing the bottom surface of the key recess along the radial direction of the rotation shaft, two side walls of the axial direction separation prevention groove may be formed obliquely to be apart from each other as being away from the Oldham ring, and the axial direction separation prevention portion may include two inclination surfaces formed obliquely to correspond to the two side walls of the axial direction separation prevention groove, respectively, and a connection surface that is formed to connect the two inclination surfaces to each other.

In the scroll compressor, the wear preventing member may further include a third reinforcement plate that is formed to connect the first reinforcement plate and the second reinforcement plate to each other, and is kept in close with the bottom surface of the key recess, and the axial direction separation prevention portion may be formed on the third reinforcement plate or may be formed on a border between the first reinforcement plate and the third reinforcement plate and on a border between the second reinforcement plate and the third reinforcement plate.

In the scroll compressor, the radial direction separation prevention unit may include a first radial direction separation prevention portion that is connected to one end of the first reinforcement plate, and a second radial direction separation prevention portion that is connected to one end of the second reinforcement plate, each of the first radial direction separation prevention portion and the second radial direction separation prevention portion may include a fixation that is connected to one end of the first reinforcement or one of the second reinforcement plate, and a free end that is formed in a direction opposite to a direction of the fixation end, and the free end of the first radial direction separation prevention portion and the free end of the second radial direction separation prevention portion may be at some distance away from each other.

In the scroll compressor, a maximum distance in a circumferential direction of the rotation shaft between the first radial direction separation prevention portion and the second radial direction separation prevention portion may be longer than a distance between a first reinforcement plate and a second reinforcement plate.

In the scroll compressor, each of the first radial direction separation prevention portion and the second radial direction separation prevention portion may be formed to have a curved surface with an arcuate cross section.

In the scroll compressor, the first radial direction separation prevention portion and the second radial direction separation prevention portion may extend from the first reinforcement plate and the second reinforcement plate, respectively, in a direction of being away from each other along the circumferential direction of the rotation shaft.

In the scroll compressor, the first radial direction separation prevention portion may be formed on both ends of the first reinforcement plate, and the second radial direction separation prevention portion may be formed on both ends of the second reinforcement plate.

In the scroll compressor, the first radial direction separation prevention portion and the second radial direction separation prevention portion may first extend from the first reinforcement plate and the second reinforcement plate, respectively, to be away from each other along the circumferential direction of the rotation shaft, and then may be secondly bent to be parallel to each other along the radial direction of the rotation shaft.

In the scroll compressor, the wear preventing member may further include a first reinforcement plate and a second reinforcement plate that extend in parallel to each other along a radial direction of the rotation shaft, from positions that are at some distance away from each other, and a third reinforcement plate that is kept in close contact with the key recess, and extends in a circumferential direction of the rotation shaft to connect the first reinforcement plate and the second reinforcement plate to each other, the axial direction separation prevention portion may be configured as a fastening hole that is formed in the third reinforcement plate, the axial direction separation prevention groove may be formed in a position that faces the fastening hole, and the wear preventing member may be held securely in the key recess, with a fastening member that passes through the fastening hole and is fastened into the axial direction separation prevention groove.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments and together with the description serve to explain the principles of the disclosure.

In the drawings:

FIG. 1 is a cross-sectional view showing an inside of an electric compressor as an example of a scroll compressor according to the present disclosure;

FIG. 2 is a cross-sectional view showing a state in which an Oldham ring is coupled between a frame and an orbiting scroll in a compression unit according to FIG. 1;

FIG. 3 is an exploded perspective diagram illustrating a compression unit of FIG. 2;

FIG. 4 is a perspective diagram illustrating a state in which a wear preventing member is separated from an orbiting scroll in the compression unit of FIG. 3;

FIG. 5 is a plan-view diagram illustrating a state in which the wear preventing member is coupled to the orbiting scroll of FIG. 4;

FIG. 6 is a cross-sectional diagram taken along line “A-A” in FIG. 5;

FIG. 7 is a perspective diagram illustrating a state in which a frame and the wear preventing member of FIG. 3 are separated from each other;

FIG. 8 is a plan-view diagram illustrating a state in which the frame and the wear preventing member of FIG. 3 are coupled to each other;

FIG. 9 is a cross-sectional diagram illustrating an example in which an oil storage groove is provided in a key recess in the orbiting scroll according to the present disclosure;

FIG. 10 is a plan-view diagram illustrating a radial direction separation prevention portion of a wear preventing member according to another embodiment of the present disclosure;

FIG. 11 is an exploded perspective diagram illustrating a radial direction separation prevention groove according to another embodiment of the present disclosure;

FIG. 12 is is a plan-view diagram illustrating an assembled state in the radial direction separation prevention structure of FIG. 11.

FIG. 13 is an exploded perspective diagram illustrating a radial direction separation prevention structure according to another embodiment of the present disclosure;

FIG. 14 is a plan-view diagram illustrating an assembled state in the radial direction separation prevention structure of FIG. 13;

FIG. 15 is an exploded perspective diagram illustrating a wear preventing member according to another embodiment of the present disclosure;

FIG. 16 is a plan-view diagram illustrating that the wear preventing member of FIG. 15 is assembled;

FIG. 17 is an explosive perspective diagram illustrating the compression unit of FIG. 2;

FIG. 18 is a perspective diagram illustrating a state in which in the compression unit of FIG. 17, the wear preventing member is separated from the orbiting scroll;

FIG. 19 is a plan-view diagram illustrating a state in which the wear preventing member is coupled to the orbiting scroll of FIG. 18;

FIG. 20 is a cross-sectional diagram taken along line “B-B” of FIG. 19;

FIG. 21 is an explosive perspective diagram illustrating a state in which the frame and the wear preventing member of FIG. 17 are separated from each other;

FIG. 22 is a plan-view diagram illustrating a state in which the frame and the wear preventing member of FIG. 17 are coupled to each other;

FIG. 23 is a cross-sectional diagram illustrating an example where the oil storage groove is provided in the key recess of the orbiting scroll according to the present disclosure;

FIG. 24 is a plan-view diagram illustrating a radial direction separation prevention portion of a wear preventing member according to the present disclosure;

FIG. 25 is an exploded perspective diagram illustrating a radial direction separation prevention groove according to another embodiment of the present disclosure;

FIG. 26 is a plan-view diagram illustrating an assembled state of the radial direction separation prevention groove of FIG. 25;

FIG. 27 is an exploded perspective diagram illustrating a radial direction separation prevention structure according to the present disclosure;

FIG. 28 is a plan-view diagram illustrating an assembled state in the radial direction separation prevention structure;

FIG. 29 is an exploded perspective diagram illustrating a wear preventing member according to another embodiment of the present disclosure;

FIG. 30 is a plan-view diagram illustrating that the wear preventing member of FIG. 29 is assembled;

FIG. 31 is an exploded perspective diagram illustrating a wear preventing member and a key recess according to another embodiment of the present disclosure;

FIG. 32 is an exploded perspective diagram illustrating the wear preventing member and the key recess of FIG. 21.

FIG. 33 is an exploded perspective diagram illustrating a wear preventing member and a key recess according to another embodiment of the present disclosure;

FIG. 34 is an exploded perspective diagram illustrating the wear preventing member and the key recess of FIG. 33;

FIG. 35 is an exploded perspective diagram illustrating a wear preventing member and a key recess according to another embodiment of the present disclosure; and

FIG. 36 is an exploded perspective diagram illustrating a wear preventing member and a key recess according to another embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

Hereinafter, a scroll compressor according to the present disclosure will be described in detail with reference to an embodiment shown in the accompanying drawings.

For the sake of brief description with reference to the drawings, the same or equivalent components will be provided with the same reference numbers, and description thereof will not be repeated.

It will be understood that when an element is referred to as being “connected with” another element, the element can be connected with the another element or intervening elements may also be present. In contrast, when an element is referred to as being “directly connected with” another element, there are no intervening elements present.

A singular representation may include a plural representation unless it represents a definitely different meaning from the context.

FIG. 1 is a cross-sectional view showing the inside of an electric compressor as an example of a scroll compressor according to the present disclosure, and FIG. 2 is a cross-sectional view showing a state in which an Oldham ring is coupled between a frame and an orbiting scroll in a compression unit according to FIG. 1.

As shown in these figures, the scroll compressor according to the present embodiment includes a driving motor 103 which is a motor part and a compression unit 105 compressing a refrigerant using a rotational force of the driving motor 103 inside a compressor casing 101.

The compressor casing 101 is provided with an intake port 111 a to which a suction pipe is connected and an exhaust port 121 a to which a discharge pipe is connected. A suction space S1 communicates with the intake port 111 a and a discharge space S2 communicates with the exhaust port 121 a. The driving motor 103 is installed in the suction space S1, and the compressor of the present embodiment is a low pressure type compressor.

The compressor casing 101 includes a main housing 110 in which the driving motor 103 is installed and a rear housing 120 coupled to an opened rear end of the main housing 110. An inner space of the main housing 110 forms the suction space S1 together with one side surface of the compression unit 105 and an inner space of the rear housing 120 forms the discharge space S2 together with the other side surface of the compression unit 105. In the rear housing 120, the above-described exhaust port 121 a is formed.

The main housing 110 has a cylindrical portion 111 formed in a cylindrical shape and a front end of the cylindrical portion 111 is integrally extended to form a closed portion 112. The rear end of the cylindrical portion 111 is opened and the rear housing 120 is sealed and coupled.

Meanwhile, the driving motor 103 constituting a motor part is press-fitted into the main housing 110. The driving motor 103 includes a stator 131 fixed inside the main housing 110 and a rotor 132 positioned inside the stator 131 and rotated by interaction with the stator 131.

The stator 131 is fixed as a stator core (no reference numeral) is shrink-fitted to the inner circumferential surface of the main housing. In the rotor 132, the rotating shaft 133 is press-fitted to the inner circumferential surface of the rotor core (no reference numeral).

The rotating shaft 133 is coupled to the center of the rotor 132 and a rear end facing the compression unit 105 is supported by the frame 140 (to be described) and the fixed scroll 150 in a cantilevered manner.

The compression unit 105 includes the frame 140, a fixed scroll (hereinafter referred to as a first scroll) 150 supported by the frame 140, and an orbiting scroll (hereinafter referred to as a second scroll) 160 provided between the frame 140 and the first scroll 150 and making an orbiting movement.

The frame 140 is coupled to the front opening of the main housing 110, the first scroll 150 is fixedly supported on the rear surface of the frame 140 and the second scroll 160 is rotataby supported on the rear surface of the frame 140 to perform an orbiting movement between the first scroll 150 and the frame 140. The second scroll 160 is eccentrically coupled to the rotating shaft 133 coupled to the rotor 132 of the driving motor 103 and performs an orbiting movement relative to the first scroll 150 to form a pair of two pair of compression chambers V including suction chamber, an intermediate pressure chamber, and a discharge chamber.

The frame 140 includes a frame disk plate portion 141 having a disk shape and a frame side wall portion 142 protruding from a rear side surface toward the first scroll 150 to allow the side wall portion 152 of the first scroll 150 to be described later.

A frame thrust surface 143 is formed on the inner side of the frame side wall portion 142 and supported by the second scroll 160 to be axially supported. A back pressure space 144 in which a portion of a refrigerant compressed in the compression chamber V is filled with oil to support the back surface of the second scroll 160 is formed. Accordingly, the pressure in the back pressure space 144 forms an intermediate pressure between the pressure in the suction space S1 and the final pressure (i.e., the discharge pressure) in the compression chamber V. Here, the axial direction refers to an extending direction of the rotation shaft 133.

A frame shaft hole 145 through which the rotating shaft 133 passes is formed in the back pressure space 144 and a first bearing (not shown) is provided on the inner circumferential surface of the frame shaft hole 145. The first bearing may be made of a bush bearing, but in some cases, it may be a ball bearing. However, since the bush bearing is less expensive than the ball bearing, it is advantageous not only in cost but also in ease of assembly and weight and noise reduction.

On the inner side of the frame thrust surface 143, a second key recess 146 is formed in which a second key portion 176 of an Oldham ring 170 to be described later is slidably inserted. Two second key recesses 146 are typically formed at intervals of 180 degrees. The second key recesses 146 will be described later together with a wear preventing member (or a friction preventing member).

Meanwhile, the first scroll 150 may be fixedly coupled to the frame 140 or may be press-fitted into the casing 110 to be fixed.

The first scroll 150 has a fixed scroll disk plate portion 151 (hereinafter, fixed side disk plate portion) 151 having a substantially disk shape and a fixed scroll side wall portion (hereinafter, first side wall portion) 152 formed at the edge of the fixed side disk plate portion 151 and coupled to the side wall portion 142 of the frame 140. On a front surface of the fixed side disk plate portion 151, a fixed side wrap 153 which is engaged with the orbiting side wrap 162 to be described later and constitutes the compression chamber (V) is formed.

A suction flow path (not shown) is formed at one side of the first side wall portion 152 so that the suction space S1 and a suction chamber (not shown) communicate with each other, and a discharge port 155 communicating with the discharge chamber and discharging a compressed refrigerant to the discharge space S2 is formed at a central portion of the fixed side disk plate portion 151.

Meanwhile, the second scroll 160 is provided between the frame and the first scroll 150, and eccentrically coupled to a rotating shaft 133 to perform an orbiting movement.

In the second scroll 160, an orbiting scroll disk plate portion (hereinafter, orbiting side disk plate portion) 161 is formed to have a substantially disc shape, and an orbiting side wrap 162 engaged with the fixed side wrap 153 to form a compression chamber is formed on the rear surface of the orbiting side disk plate portion 161. The orbiting side wrap 162 may have an involute shape together with the fixed side wrap 153, but it may also have various other shapes.

On the front surface of the orbiting side disk plate portion 161, a scroll-side thrust surface 165 corresponding to the frame-side thrust surface 143 and forming a thrust surface is formed. However, since the second scroll 160 floats against the frame 140 when the compressor is driven, the frame-side thrust surface 143 and the scroll-side thrust surface 165 are substantially not in contact with each other. Rather, the frame 140 and the second scroll 160 form a thrust surface with the ring portion 171 of the Oldham ring 170 to be described later.

A first key recess 166 into which the first key portion 175 of the oval bearing 170 to be described later is slidably inserted is formed in the middle of the scroll-side thrust surface 165. Two first key recesses 166 are formed at intervals of 180 degrees. The first key recess 166 is formed with a phase difference of about 90 degrees with the second key recess 146 in an axial direction projection. The first key recess will be described later together with the friction preventing member.

Meanwhile, a rotation preventing mechanism is provided between the frame 140 and the second scroll 160 to prevent rotation of the second scroll 160. The rotation preventing mechanism may be installed between the first scroll 150 and the second scroll 160 in some cases. Hereinafter, an example in which the rotation preventing mechanism is provided between the frame 140 and the second scroll 160 will be described as an example.

The rotation preventing mechanism may be a pin-and-ring type as described above, or an Oldham ring type. The present embodiment relates to the case where the Oldham ring e is applied.

The Oldham ring includes a ring portion 171 formed in an annular shape and a plurality of first key portions 175 and a plurality of second key portions 176 protruding from both side surfaces in the axial direction of the ring portion 171. The structure of the Oldham ring will be described later together with the friction preventing member.

In the figure, the reference numeral 137 is a balance weight.

The scroll compressor according to this embodiment operates as follows.

That is, when power is applied to the driving motor 103, the rotating shaft 133 rotates together with the rotor 132 to transmit a rotational force to the second scroll 160, and the second scroll 160 makes an orbiting movement by the Oldham ring which is a rotation preventing mechanism, and thus, the compression chamber V is continuously moved toward the center side and the volume of the compression chamber V is reduced.

The refrigerant flows into the suction space Si through the intake port 111 a and the refrigerant introduced into the suction space S1 passes through a flow path formed in the outer circumferential surface of the stator 131 and the inner circumferential surface of the main housing 110 or an air gap between the stator 131 and the rotor 132 and is sucked to the compression chamber V through a suction flow path 154.

At this time, a part of the refrigerant sucked into the suction space S1 through the intake port 111 a first comes into contact with closed portion 112 which is the front surface of the main housing 110, before passing through the driving motor 103. Accordingly, the closed portion 112 is heat-exchanged with the cold suction refrigerant and cooled, thereby dissipating heat in an inverter module (not shown) attached to the closed portion 112 of the main housing 110.

The refrigerant sucked into the compression chamber V through the suction space S1 is compressed by the first scroll 150 and the second scroll 160 and is discharged into the discharge space S2 through the discharge port 155. Oil of the refrigerant discharged to the discharge space S2 is separated at the discharge space S2 and the refrigerant is discharged to the refrigerating cycle through the exhaust port 121 a while the oil is collected at a lower portion of the discharge space S2 and supplied to the respective bearing surfaces or to the compression chamber through an oil flow path (not shown).

At this time, a part of the oil flows into a space between the frame 140 and the second scroll 160 to lubricate between the Oldham ring 170 and the frame 140 to which the Oldham ring 170 is coupled or the second scroll 160.

Meanwhile, the scroll compressor as described above is widely applied not only to an air conditioning system in a building but also to an air conditioning system in a vehicle. Scroll compressors may increase compressor efficiency by reducing a weight of a moving member, similarly to other compressors. Particularly, when installed in a vehicle, it is advantageous to reduce the weight of the compressor since the weight of the entire compressor as well as the rotating member is related to the weight of the vehicle.

Accordingly, in a scroll compressor (generally called an electric scroll compressor) applied to a vehicle, a casing, a frame, a fixed scroll and an orbiting scroll as well as an Oldham ring may be made of a lightweight material such as aluminum (aluminum alloy).

However, as described above, when the Oldham ring and the frame or the orbiting scroll contacting the Oldham ring is formed of an aluminum material, friction characteristics depending on the same material may be deteriorate, unlike cast iron.

Taking this into consideration, it is considered to form the ring portion and the key portion of the Oldham ring by different materials and assembled or to form the entire Oldham ring of the same material and form a coating layer for improving friction characteristics on the surface of the Oldham ring. However, these methods have limitations in workability and reliability as described above.

Accordingly, the present disclosure is to improve the workability of the above-mentioned bearing by forming the entire Oldham ring with the same kind of material and forming the frame or the orbiting scroll to which the Oldham ring is coupled with the same material as the Oldham ring, while preventing deterioration of friction characteristics according to the same material, to ensure the reliability of the compressor.

FIG. 3 is an exploded perspective diagram illustrating the compression unit of FIG. 2. FIG. 4 is a perspective diagram illustrating a state in which the wear preventing member is separated from the key recess in the orbiting scroll in the compression unit of FIG. 3. FIG. 5 is a plan-view diagram illustrating a state in which the wear preventing member is coupled to the key recess of the orbiting scroll of FIG. 4. FIG. 6 is a cross-sectional diagram taken along line “A-A” in FIG. 5.

As illustrated, a frame 140, in the present embodiment, a second scroll 160, and an Oldham ring 170 are all formed of aluminum material that has lighter weight than cast iron. A specific gravity of cast iron is approximately 7.85, and a specific gravity of aluminum alloy is approximately 2.8. Therefore, in a case where the frame, the second scroll, and the Oldham ring are formed of aluminum material, a weight of the compressor can be reduced.

The Oldham ring 170 is configured with a ring portion 171 is formed in the shape of a ring and a first key portion 175 and a second key portion 176 that protrude from both flank surfaces in the axial direction, respectively, of the ring portion 171. Multiple first key portions 175 are formed on one flank surface in the axial direction, of the ring portion 171, and multiple second key portions 176 are formed on the other flank surface in the axial direction, of the ring portion 171. Multiple first key portions 175 and second key portions 176 are formed to be spaced apart at an interval of 180°, and the first key portion 175 and the second key portion 176, when projected, are formed at an interval of 90° with respect to each other.

The first key portion 175 and the second key portion 176 each are formed in the shape of a rectangular cross section that extends over a long distance in the radial direction. However, depending on the situation, the first key portion 175 and the second key portion 176 may be formed in the shape of a square cross section or in the shape that has approximately the same length. This will be further described below along the key recess.

The ring portion 171 and the key portions 175 and 176 are formed into a single body. That is, the first key portion 175 and the second key portion 176 are formed to extend in a manner that is combined integrally with the ring portion 171. Accordingly, the ring portion 171 and the key portions 175 and 176 are formed of the same material. That is, the entire Oldham ring is formed of aluminum material.

On the other hand, multiple first key recesses 166 that correspond to first key portions 175, respectively, of the Oldham ring 170 are formed in the second scroll 160. Multiple second key recesses 146 that correspond to the second key portions 176, respectively, of the Oldham ring 170 are formed in the frame 140.

Multiple first key recesses 166 and second key recesses 146 are formed in surfaces, respectively, that face each other. That is, the second scroll 160 has a surface facing toward a first scroll 150 and a surface facing toward the frame 140, which is positioned in the opposite direction, and the first key recess 166 is formed in the surface facing the frame 140. Likewise, the frame 140 has a surface facing toward the second scroll 160 and a surface facing toward drive motor 103, which is positioned in the opposite direction, and the second key recesses 146 is formed in the surface facing toward the second scroll 160.

The first key recess 166 in the second scroll 160 and the second key recesses 146 in the frame 140 are formed in a manner that extends over a sufficiently long distance in the radial direction compared with the first key portion 175 and the second key portion 176 of the Oldham ring 170. The radial direction here refers to the radial direction of a rotation shaft 133. The radial direction of the rotation shaft 133 refers to a direction that orthogonally intersects the axial direction of the rotation shaft 133.

The first key recess 166 and the second key recesses 146 have such a width that they almost come into contact with flank surfaces, respectively, of the first key portion 175 and the second key portion 176 in the circumferential direction. The circumferential direction here refers to the circumferential direction of the rotation shaft 133.

Accordingly, the first key portion 175 and the second key portion 176 of the Oldham ring 170 are slid in the radial direction into the first key recess 166 in the second scroll 160 and the second key recess 146 in the frame 140, respectively, and thus transfer forces in the circumferential direction.

Wear preventing members 180 are installed between the first key recess 166 and the first key portion 175 and between the second key recesses 146 and the second key portion 176, respectively. Specifically, the wear preventing members 180 are inserted between a flank surface in the circumferential direction, of the first key recess 166 and a flank surface in the circumferential direction, of the first key portion 175, and between a flank surface in the circumferential direction, of the second key recesses 146 and a flank surface in the circumferential direction, of the second key portion 176, respectively.

It is desirable that the wear preventing member 180 is formed of material that has greater stiffness than that of the second scroll 160, the frame 140 or the Oldham ring 170, that is, material that is different from that of the second scroll 160, the frame 140, or the Oldham ring 170.

Thus, when the first key portion 175 and the second key portion 176 move in a sliding manner along the first key recess 166 and the second key recesses 146, respectively, the key portions 175 and 176 of the same material are prevented from being brought into direct contact with the key recesses 166 and 146, respectively. Thus, the second scroll 160, the frame 140, or the Oldham ring 170 can be manufactured of light-weight material, and the second scroll 160, the key recesses 166 and 146 in the frame 140, or the key portions 175 and 176 of the Oldham ring 170 can be prevented from being worn.

The wear preventing member and the key recess into which the wear preventing member is inserted will be in detail described below. The first key recess 166, the first key portion 175, and the wear preventing member 180 that is provided between these are the same as the second key recess 146, the second key portion 176, and the wear preventing member that is provided between these, respectively. Therefore, the first key recess 166, the first key portion 175, and the wear preventing member 180 that is provided between the first key recess 166, the first key portion 175 are described representatively.

With reference again to FIGS. 3 and 4, the first key recess 166 is formed in the shape of a slit that has a prescribed length in the radial direction. Accordingly, the first key recess 166 has a first side wall 166 a and the second side wall 166 b that face each other in the circumferential direction, a front surface makes up a bottom surface 166 c in the axial direction, and a rear surface, which is opposite in direction to the bottom surface 166 c, makes up an opening 166 d in the axial direction. Then, an external opening 166 e is formed in an external end that corresponds to a circumference of the second scroll 160, so that the first key portion 175 comes in and goes out, and an internal opening 166 f is formed in an internal end that is opposite in direction to the external end, so as to communicate with a radial direction separation prevention groove 167 that will be described below.

As illustrated in FIG. 5, the first side wall 166 a and the second side wall 166 b are formed to be parallel to each other in the radial direction. The first side wall 166 a and the second side wall 166 b are formed to face each other, from positions that are at some distance away from each other in the circumferential direction. The first side wall 166 a is formed to be kept in close contact with a first reinforcement plate 181 a of the wear preventing member 180, which will be described below. The second side wall 166 b is formed to be kept in close contact with a second reinforcement plate 181 b of the wear preventing member 180, which will be described below.

The first side wall 166 a and the second side 166 b are formed in a manner that a gap (hereinafter referred to a first gap) L1 between the first side wall 166 a and the second side wall 166 b is shorter than a length (hereinafter referred to as a second length) L2 in the radial direction, of each of the first side wall 166 a and the second side wall 166 b.

The bottom surface 166 c of the first key recess 166 is formed to connect the first side wall 166 a and the second side wall 166 b along the circumferential direction. The bottom surface 166 c faces the first key portion 175 that is inserted into the first key recess 166.

The internal opening 166 f may also be formed to be closed in the shape of a semicircle at the internal ends of the first side wall 166 a and the second side wall 166 b. However, in the present embodiment, the radial direction separation prevention groove 167 is formed at an inner side (inwards from) the internal opening 166 f so that the wear preventing member 180 is held securely. The radial direction separation prevention groove 167 prevents the wear preventing member 180 from being separated, along with a radial direction separation prevention portion 182 of the wear preventing member 180, which will be described below.

A cross section of the radial direction separation prevention groove 167 extends from the internal ends of the first side wall 166 a and the second side wall 166 b and is formed in the shape of a circular segment that is more similar to a circle than to a semicircle. Accordingly, the radial direction separation prevention groove 167 is formed in a shape that an internal diameter L3 of the radial direction separation prevention groove 167 is greater than the first gap L1, and an imaginary line, which connects between a portion of the first side wall 166 a, to which one end of the radial direction separation prevention groove 167 is coupled, and a portion of the second side wall 166 b, to which the other end of the radial direction separation prevention groove 167 is coupled, is gradually lengthened up to a radius of the radial direction separation prevention groove 167. In other words, the radial direction separation prevention groove 167 is formed so that a circumferential direction maximum length L3 between internal wall surfaces 167 a of the radial direction separation prevention groove 167 is greater than the first gap L1.

On the other hand, the first key portion 175 includes a first key surface 175 a that corresponds to the first side wall 166 a, and a second key surface 175 b that corresponds to the second side wall 166 b. Accordingly, the first key portion 175, when projected in the axial direction, may be formed in the shape of a square or rectangular cross section as illustrated in FIG. 5.

In a case where the first key portion 175 is formed in the shape of a square (or is formed to have a width that is the same as that in the radial direction, of the ring portion), a length in the radial direction, of the first key portion 175 is shortened. Thus, the length, in the radial direction, of the first key portion 175 is shortened, and an internal diameter of the ring portion 171 is all the more increased. Thus, a backing space 144 of the frame 140 that is formed inside of the ring portion 171 is increased.

On the other hand, in a case where the first key portion 175 is formed in the shape of a rectangle (or is formed to have a width that is greater than a radio direction width of the ring portion), the length in the radial direction, of the first key portion 175 is increased and vibration of the Oldham ring 170 is all the more decreased. Thus, leakage from the compression chamber is suppressed.

In addition, the first key portion 175 is formed in a manner that a length L4 in the radial direction, of the first key portion 175 is shorter than a length in the radial direction, of the first key recess 166, which is the second length L2. Accordingly, the first key portion 175 moves in a sliding manner in a space between the first side wall 166 a and the second side wall 166 b, and thus the first key portion 175 does not move into the radial direction separation prevention groove 167. Even if the first key portion 175 moves into the radial direction separation prevention groove 167, in order to stably support the first key portion 175, it is desirable that the first key portion 175 moves into the radial direction separation prevention groove 167 by only a distance that is less than one half of the length L4 in the radial direction, of the first key portion 175.

On the other hand, the wear preventing member 180 may be formed by bending a member having a U-shaped cross section or may be formed by molding a high molecular material. That is, the wear preventing member 180 includes the first reinforcement plate 181 a and the second reinforcement plate 181 b that are arranged in parallel to each other in the radial direction, and the radial direction separation prevention portion 182 that connects between the first reinforcement plate 181 a and the second reinforcement plate 181 b.

The first reinforcement plate 181 a and the second reinforcement plate 181 b extend in parallel to each other along the radial direction of the rotation shaft 133, from positions that are at some distance away from each other. The first reinforcement plate 181 a is kept in close contact with the first side wall 166 a of the first key recess 166. The second reinforcement plate 181 b is kept in close contact with the second side wall 166 b of the first key recess 166. Two surfaces, one of the first reinforcement plate 181 a and one of the second reinforcement plate 181 b, which faces each other, correspond to the first key surface 175 a and the second key surface 175 b, respectively, of the first key portion 175 with a lubrication gap in between.

As illustrated in FIGS. 4 and 5, the radial direction separation prevention portion 182 is formed by bending one end of the first reinforcement plate 181 a and one end of the second reinforcement plate 181 b, which face each other, and extending to connect the first reinforcement plate 181 a and the second reinforcement plate 181 b. Accordingly, the firm adhesion of the first reinforcement plate 181 a and the second reinforcement plate 181 b to the first side wall 166 a and the second side wall 166 b possible with an elastic force of the radial direction separation prevention portion 182.

The radial direction separation prevention portion 182 protrudes from each of one end of the first reinforcement plate 181 a and one end of the second reinforcement plate 181 b to prevent the wear preventing member 180 from being separated from the first key recess 166 along the radial direction of the rotation shaft 133. The radial direction separation prevention portion 182 may be formed as one end of the first reinforcement plate 181 a and one end of the second reinforcement plate 181 b protrude and then are connected to each other so that the radial direction separation prevention portion 182 has a curved surface with a cross section in the shape of a circular arc (or the arcuate shape), but no limitation to this is necessarily imposed.

The radial direction separation prevention portion 182 is formed such that an external surface of the radial direction separation prevention portion 182 is kept in close contact with an inner circumferential surface 167 a of the radial direction separation prevention groove 167. For example, an internal diameter L3′ that is a circumferential direction maximum gap that is defined by the radial direction separation prevention portion 182 is greater than a circumferential direction gap L1 that is defined by an internal surface of each of the first reinforcement plate 181 a and the second reinforcement plate 181 b. The circumferential direction maximum gap L3′ that is defined by the radial direction separation prevention portion 182 refers to a diameter of a circle that corresponds to a circular arc that is formed by the radial direction separation prevention portion 182.

In order for a value of L3′ to be greater than a value of L1, a central angle of the circular arc has to be greater than 90°. If a magnitude of the central angle is 90°, the value of L3′ is equal to the value of L1. The value of L3′ increases until the magnitude of the central angle reaches 180°. If the magnitude of the central angle is equal to or greater than 180°, the value of L3′ no longer increases and is constant. In order to reliably prevent the wear preventing member 180 from being separated in the radial direction, it is desirable that the magnitude of the central angle is equal to or greater than 180°.

Accordingly, an outer circumferential surface of the radial direction separation prevention portion 182 is kept in close contact with the inner circumferential surface 167 a of the radial direction separation prevention groove 167, and thus the wear preventing member 180 is suppressed from being separated in the radial direction of the rotation shaft 133, that is, in a direction toward the external opening 166 e in the first key recess 166. In order to prevent the wear preventing member 180 from being separated in the direction toward the external opening 166 e in the first key recess 166, the radial direction separation prevention portion 182 has to be positioned closer to the rotation shaft 133 than the first reinforcement plate 181 a or the second reinforcement plate 181 b. Likewise, the radial direction separation prevention groove 167 has to be closer to the rotation shaft 133 than the first key recess 166.

At this point, as illustrated in FIG. 6, the wear prevention member 180 is formed such that a height in the axial direction thereof is at least the same as a depth of the first key recess 166. However, the wear prevention member 180 may be formed such that the height in the axial direction thereof is somewhat smaller than the depth of the first key recess 166.

On the other hand, as described above, the second key recess 146 is formed in a second frame, so that the second key portion 176 of the Oldham ring is inserted in a sliding manner. FIG. 7 is a perspective diagram illustrating a state in which the frame and the wear preventing member of FIG. 3 are separated from each other. FIG. 8 is a plan-view diagram illustrating a state in which the frame and the wear preventing member of FIG. 3 are coupled to each other.

As illustrated, the second key recesses 146 in the frame 140 and the second key portion 176 of the Oldham ring 170 are also formed in the same shape than the first key recess 166 in the second scroll 160 and the first key portion 175 of the Oldham ring 170, which are described above.

However, the friction prevention member 180 that is inserted between the second key recesses 146 and the second key portion 176 and between the second key recesses 146 and the second key portion 176, and the friction prevention member 180 that is inserted between the first key recess 166 and the first key portion 175 and between the first key recess 166 and the first key portion 175, which are described above, are the same in shape, but are opposite in the inward direction and the direction.

In addition, the friction prevention member 180 and the separation prevention portions including the separation prevention groove 147 that prevents the friction prevention member 180 from being separated are also the same in shape as the embodiments described above. Therefore, the detailed descriptions of these are not repeated.

The scroll compressor according to the embodiment, as described above, has the following effects.

That is, the friction prevention member 180 are inserted between the first key recess 166 and the first key portion 175 and between the second key recesses 146 and the second key portion 176, respectively. Thus, the first key portion 175 of the Oldham ring 170 is prevented from being brought into direct contact with the first key recess 166 in the second scroll 160, and the second key portion 176 of the Oldham ring 170 is prevented from being brought into direct contact with the second key recesses 146 in the frame 140.

Accordingly, although the second scroll 160, the frame 140, and the Oldham ring 170 are all made of the same type of material, specifically, aluminum material that has a lower degree of hardness than cast iron, a decrease in a friction characteristic between the Oldham ring 170 and the second scroll 160 and between the Oldham ring 170 and the frame 140 is suppressed, and the reliability of the compressor is improved.

In addition, the second scroll 160, the frame 140, and the Oldham ring 170 are all formed of light-weight aluminum material, and thus the weight of the compressor is reduced. This contributes to an increase in the efficiency of the compressor and of an apparatus that uses the compressor.

In addition, the ring portion 171 of the Oldham ring 170 and the key portions 175 and 176 are formed into a single body and thus connection parts of the ring portion and the key portion are sufficiently reinforced. Accordingly, the ring portion 171 and the key portions 175 and 176 are suppressed from being damaged due to application of force. This contributes to an increase in the reliability of the compressor.

In addition, the ring portion 171 of the Oldham ring 170 and the key portions 175 and 176 are formed into a single body, and thus a machining error between the ring portions 171 and the each of key portions 175 and 176 or deformation of the key portions 175 and 176 are minimized. Accordingly, the separation of the key portion from the key recess in a undesirable direction when driving the compressor is minimized and thus a compression loss due to a gap between wraps is suppressed.

In addition, a separate coating layer does not need to be formed on a surface of the Oldham ring 170, Thus the cost of manufacturing the Oldham ring 170 is reduced, and damage to the Oldham ring and a loss of frictional force thereof are suppressed.

On the other hand, in the embodiment described above, the separation prevention groove may form a type of oil storage space. Thus, while the compressor does not operate, as well as while the compressor operates, a fixed amount of oil can be stored. The stored oil flows between the key recess and the key portion, more precisely, between the key portion and the friction prevention member for lubrication. Thus, the wear of the key portion can be suppressed more effectively. Therefore, a bottom surface of the radial direction separation prevention groove 167 is formed to have the same height as the bottom surface of the first key recess 166.

However, as illustrated in FIG. 9, depending on the situation, the radial direction separation prevention groove 167 is formed such that a bottom surface depth thereof is greater than a bottom surface depth of the first key recess 166. Accordingly, an oil storage groove 167 b is formed in the bottom surface of the radial direction separation prevention groove 167.

The oil storage groove 167 b, as described above, may be formed in the bottom surface of the separation prevention groove, but no limitation to the separation prevention groove needs to be necessarily imposed. That is, the formation of the oil storage groove 167 b out of a range where the key portion moves is sufficient. For example, even if a separate separation prevention groove is not formed, during a machining process, a groove in the shape of a semicircle is formed in an end portion of the key recess. The oil storage groove 167 b may be formed in this groove.

As described above, in a case where the oil storage groove 167 b is formed in the radial direction separation prevention groove 167, oil that is introduced into the first key recess 166 is stored in the oil storage groove 167 b. When the compressor operates, a fixed amount of oil is supplied between the first key recess 166 and the first key portion 175.

On the other hand, in the embodiment described, a connection surface that defines a radial direction separation prevention protrusion portion is formed in the shape of a circle, but as illustrated in FIG. 10, a connection surface 182 may be formed in the shape of a rectangle. In this case, it is desirable that the radial direction separation prevention groove 167 is also formed in the same shape as the connection surface 182, that is, in the shape of a rectangle.

As described above, the radial direction separation prevention groove 167 and the connection surface 182, that is, the connection surface 182 that makes up the radial direction separation prevention protrusion portion is formed in the shape of a rectangle, and thus force in the radial direction that supports the friction prevention member 180 is increased much more. For this reason, the separation of the friction prevention member 180 can be suppressed more effectively.

In addition, on the other hand, a structure that securely holds a friction prevention member according to another embodiment of the present disclosure is as follows.

That is, in the embodiments described above, the connection surface of the friction prevention member is inserted into the separation prevention groove to securely hold the friction prevention member, but in the present embodiment, a first reinforcement surface and a second reinforcement surface of the friction prevention member are inserted into the separation prevention groove to provide support. FIG. 11 is an exploded perspective diagram illustrating a separation prevention according to another embodiment of the present disclosure. FIG. 12 is a schematic diagram for describing an internal diameter of a key recess of FIG. 11.

As illustrated, in the present embodiment, the separation prevention groove is not formed outside of the first key recess 166. Instead, a first separation prevention groove 166 c 1 is formed in a first key recess 167, that is, at an inner side of a first key recess surface 166 a that comes perpendicularly into contact with the bottom surface, and a second separation prevention groove 166 c 2 is formed at an inner side of a second key recess surface 166 b.

In the same manner as the first key recess surface 166 a and the second key recess surface 166 b, the first separation prevention groove 166 c 1 and the second separation prevention groove 166 c 2 are formed to be parallel to each other. An external end of the first separation prevention groove 166 c 1 and an external end of the second separation prevention groove 166 c 2 are formed to be located almost at the same positions as external ends of the first key recess surface 166 a and the second key recess surface 166 b, respectively.

Then, a third separation prevention groove 166 c 3, with which the bottom surface and an internal surface of the first key recess 166 perpendicularly come into contact, is formed. The third separation prevention groove 166 c 3 connects internal ends of the first separation prevention groove 166 c 1 and the second separation prevention groove 166 c 2. The third separation prevention groove 166 c 3 is formed to have a curved surface, and, depending on the situation, may be formed to have a straight-line surface.

At this point, the first separation prevention groove 166 c 1, the second separation prevention groove 166 c 2, and the third separation prevention groove 166 c 3 are formed to the same depth, and are formed to such a depth that one end in the axial direction, of the friction prevention member 180 is inserted and is supported in the radius direction.

As described, in a case where the separation prevention grooves 166 c 1 to 166 c 3 that prevent the friction prevention member 180 from being separated are not formed outside of the first key recess 166, and are instead formed inside of the first key recess 166, the separation of the friction prevention member 180 can also be effectively suppressed.

Furthermore, in this case, from the perspective of the second key recess, because the separation prevention groove is not formed outward with respect to the radius direction of the second key recesses 146, the second key recesses 146 can be moved outward by a radius of the separation prevention groove. Accordingly, the internal diameter of the ring portion 171 of the Oldham ring 170 can be increased and thus an internal diameter D1 of the backing space 144 can be increased. As a result, by increasing an area of the backing space 144, an area of the second scroll 160, on which backpressure is exerted, can be increased, and the behavior of the second scroll 160 can be stabilized.

In addition, on the other hand, a structure that securely holds a friction prevention member according to still another embodiment of the present disclosure is as follows.

That is, in the embodiments described above, the friction prevention member is securely held using the separation prevention groove that is provided in the vicinity of the key recess, and in the present embodiment, the friction prevention member is held in place using a separate fixation pin.

For example, as illustrated in FIGS. 13 and 14, a fixation pin 185 may be pressure-pushed inward from the connection surface 182 of the friction prevention member 180, which is positioned at the deepest position in the first key recess 166, that is, positioned farthest from the center, and thus a connection surface 183 of the friction prevention member 180 may be supported by the fixation pin 185 in the radius direction.

In this case, a separate separation prevention groove does not need to be formed in the vicinity of the first key recess 166, and the friction prevention member does not also need to be formed by enlarging the connection surface. Therefore, in this case, the machining of the key recess and the manufacturing of the friction prevention member can also be facilitated.

Furthermore, in this case, as described above, from the perspective of the second key recess, a separate separation prevention groove also does not need to be formed. Because of this, an internal diameter of the Oldham ring can be increased. As a result, the behavior of the second scroll can be stabilized by increasing the area of the backing space.

In addition, on the other hand, a structure that securely holds a friction prevention member according to still another embodiment of the present disclosure is as follows.

That is, in the embodiments described above, the friction prevention member is provided only in both key recess surfaces of the key recess, but in the present embodiment, the friction prevention member is provided in not only the both key recess surfaces but also a bottom surface of the key recess. FIG. 15 is an exploded perspective diagram illustrating a wear preventing member according to another embodiment of the present disclosure. FIG. 16 is a plan-view diagram illustrating that the wear preventing member of FIG. 15 is assembled.

As illustrated, a friction prevention member 180 according to the present embodiment includes a first reinforcement surface 181 a and a second reinforcement surface 181 b, and a third reinforcement surface 181 c that is formed between the first reinforcement surface 181 a and the second reinforcement surface 181 b.

The first reinforcement surface 181 a and the second reinforcement surface 181 b are formed to be parallel to each other. The third reinforcement surface 181 c is formed by circumferentially extending from one end of the first reinforcement surface 181 a and one end of the second reinforcement surface 181 b, which are formed in the axial direction and face each other in the circumferential direction, so as to connect the first reinforcement surface 181 a and the second reinforcement surface 181 b.

In addition, the third reinforcement surface 181 c corresponds to the bottom surface of the first key recess 166. Accordingly, the friction prevention member 180 is provided to surround an entire internal surface of the first key recess 166 except for an opening surface 166 d in the axial direction, of the first key recess 166 that is opened.

At this point, separation prevention surfaces 184 a and 184 b are formed by bending in the circumferential direction an internal end of the first reinforcement surface 181 a and an internal end of the second reinforcement surface 181 b, respectively, which are formed in the radial direction and face each other in the circumferential direction, and serve to support the wear prevention member 180 in the radial direction.

The separation prevention surfaces 184 a and 184 b may be formed in the shape of a circular arc, in a manner that extends from the first reinforcement surface 181 a and the second reinforcement surface 181 b, respectively. In this case, the radial direction separation prevention groove 167 is formed, in the radius direction, inward from the first key recess 166, and both of separation prevention surfaces 184 a and 184 b is kept in close contact with an internal surface of the radial direction separation prevention groove 167.

Of course, in this case, a separation prevention groove (not illustrated) may also be formed in the bottom surface of the first key recess 166 so that the third reinforcement surface 181 c is inserted into the separation prevention groove. Furthermore, the first reinforcement surface 181 a and the second reinforcement surface 181 b may be elastically pressure-pushed into the first key recess surface 166 a and the second key recess surface 166 b, respectively, using the third reinforcement surface 181 c.

As described above, in a case where the friction prevention member 180 is formed from the first reinforcement surface 181 a, the second reinforcement surface 181 b, and the third reinforcement surface 181 c, the friction prevention member 180 surrounds not only the first key surface 175 a and the second key surface 175 b of the first key portion 175, but also third key surface 175 c that correspond to the bottom surface of the first key recess 166. As a result, while the second scroll 160, which is an orbiting scroll, performs an orbiting motion, although an inclination phenomenon occurs, the bottom surface of the first key recess 166 and the third key surface 175 c of the first key portion 175 are suppressed from being brought into direct contact with each other.

Another embodiment of the present disclosure will be described below.

FIG. 17 is an exploded perspective diagram illustrating the compression unit of FIG. 2. FIG. 18 is a perspective diagram illustrating a state in which in the compression unit of FIG. 17, the wear preventing member is separated from the key recess in the orbiting scroll. FIG. 19 is a plane-view diagram illustrating a state in which the wear preventing member is coupled to the orbiting scroll of FIG. 18. FIG. 20 is a cross-sectional diagram taken along line “B-B” of FIG. 19.

Descriptions with reference to FIGS. 17 to 20, which are the same as those with reference to FIGS. 3 to 6, are omitted. What distinguishes FIGS. 17 to 20 from the preceding figures will be described.

An axial direction separation prevention structure of the wear preventing member will be described.

With reference to FIGS. 17 and 18, the wear preventing member 180 includes an axial direction separation prevention portion 182 for preventing the separation from the first key recess 166 along the axial direction of the rotation shaft 133. Then, the second scroll 160 correspondingly includes axial direction separation prevention groove 167 that is formed as a result of recessing a surface of the first key recess 166. The axial direction separation prevention portion 182 is held in place by a circumference of the axial direction separation prevention groove 167.

One end (an internal end) of the first reinforcement plate 181 a is a fixation end that is connected to the radial direction separation prevention portion 182. In contrast with this, the other end (an external end) of the first reinforcement plate 181 a is a free end that is firmed in a direction opposite to a direction of the fixation end. The axial direction separation prevention portion 181 a 1 is formed as a result of extending from the free end of the first reinforcement plate 181 a.

Likewise, one end (an internal end) of the second reinforcement plate 181 b is a fixation end that is connected to the radial direction separation prevention portion 182. In contrast with this, the other end (an external end) of the second reinforcement plate 181 b is a free end that is formed in a direction opposite to a direction of the fixation end. An axial direction separation prevention portion 181 b 1 is formed as a result of extending from the second reinforcement plate 181 b.

The axial direction separation prevention portion 181 a 1 that is formed on the free end of the first reinforcement plate 181 a, and the axial direction separation prevention portion 181 b 1 that is formed on the free end of the second reinforcement plate 181 b are formed to be away from each other.

The axial direction separation prevention portion 181 a 1 may be formed as a result of partially cutting the free end of the first reinforcement plate 181 a along the radial direction of the rotation shaft 133. Likewise, the axial direction separation prevention portion 181 b 1 may be formed as a result of partially cutting the free end of the second reinforcement plate 181 b along the radial direction of the rotation shaft 133.

Each of the free end of the first reinforcement plate 181 a and the free end of the second reinforcement plate 181 b is divided in the axial direction into two parts, a part FE1 and a part FE2. A part that extends along a direction of extension of the first reinforcement plate 181 a or the second reinforcement plate 181 b with respect to a cutting position for forming the axial direction separation prevention portions 181 a 1 and 181 b 1 is referred to as a first part FE1. Conversely, a part that is cut off or extends from the first part FE1 to form the axial direction separation prevention portions 181 a 1 and 181 b 1 is referred to as a second part FE2.

The second part FE2 is positioned closer to the bottom surface 166 c of the first key recess 166 than the first part FE1. The axial direction separation prevention portions 181 a 1 and 181 b 1 correspond to the second part FE2, and thus the axial direction separation prevention portions 181 a 1 and 181 b 1 are formed to be positioned closer to the bottom surface 166 c of the first key recess 166 than the first part FE1.

The axial direction separation prevention grooves 168 a and 168 b are formed two side walls, side walls 166 a and 166 b, of the first key recess 166. Specifically, axial direction separation prevention grooves 168 a and 168 b are formed in the shape of a chamfer on a border between an edge of an orbiting side convex end portion 161 that is provided on the second scroll 160 and the first side wall 166 a, and on a border between the edge of the orbiting side convex end portion 161 and the second side wall 166 b, respectively.

As is the case with the wear preventing member 180, in a case where each of the two side walls, the side walls 166 a and 166 b of the first key recess 166 is divided into a first part SW1 and a second part SW2, the axial direction separation prevention grooves 168 a and 168 b are formed in the second part SW2. At this point, the first part SW1 of the two side walls, the side walls 166 a and 166 b, corresponds to a part that is positioned, along the axial direction of the rotation shaft 133, relatively farther away from the bottom surface 166 c of the first key recess 166. Then, the second part SW2 of the two side walls, the side walls 166 a and 166 b, corresponds to a part that is positioned, along the axial direction of the rotation shaft 133, relatively close to the bottom surface 166 c of the first key recess 166. The axial direction separation prevention grooves 168 a and 168 b are formed in the shape of a chamfer on a border between the edge of the orbiting side convex end portion 161 that is provided on the second scroll 160 and the second part SW2.

When the wear preventing member 180 is inserted into the first key recess 166, the axial direction separation prevention portions 181 a 1 and 181 b 1 reach stably into the axial direction separation prevention grooves 168 a and 168 b, respectively. The two side walls, the side walls 166 a and 166 b of the first key recess 166 include the first part SW1 in the radial direction with respect to the axial direction separation prevention portions 181 a 1 and 181 b 1, the axial direction separation prevention portions 181 a 1 and 181 b 1 is held in place by the first part SW1. The first par SW1 here corresponds to a circumference of the axial direction separation prevention grooves 168 a and 168 b. With this structure, the separation of the wear preventing member 180 in axial direction can be prevented.

In order for the wear preventing member 180 to reach stably into the first key recess 166, pressure is applied to the free end of the first reinforcement plate 181 a and the free end of the second reinforcement plate 181 b in a direction in which they approach each other, and then they are inserted into the first key recess 166. When the pressure is no longer applied, with the elastic force of the radial direction separation prevention portion 182, the first reinforcement plate 181 a and the second reinforcement plate 181 b is restored to extend toward a direction that they are parallel to each other, and, the axial direction separation prevention portions 181 a 1 and 181 b 1 reach stably into the axial direction separation prevention grooves 168 a and 168 b, respectively. The axial direction separation prevention portions 181 a 1 and 181 b 1 are held in place, in the axial direction, by the circumference of the axial direction separation prevention grooves 168 a and 168 b.

With the described as described above, the wear preventing member 180 is held securely without being separated, along the radial direction and the axial direction of the rotation shaft 133, from the first key recess 166.

On the other hand, as illustrated in FIG. 20, the wear preventing member 180 may be formed so that a height in the axial direction thereof is the same as at least a depth of the first key recess 166. However, the wear preventing member 180 may be formed so that the height in the axial direction thereof is somewhat smaller than the depth of the first key recess 166.

On the other hand, the second key recesses 146 is formed in the frame 140 so that the second key portion 176 of the Oldham ring 170 is inserted in a sliding manner. FIG. 21 is a perspective diagram illustrating a state in which the frame 140 and the wear preventing member 180 of FIG. 17 are separated from each other. FIG. 22 is a plan-view diagram illustrating a state in which the frame 140 and the wear preventing member 180 of FIG. 17 are coupled to each other.

As illustrated, the second key recesses 146 in the frame 140 and the second key portion 176 of the Oldham ring 170 are also formed in the same shape than the first key recess 166 in the second scroll 160 and the first key portion 175 of the Oldham ring 170, which are described above.

However, the wear preventing member 180 that is inserted between the second key recesses 146 and the second key portion 176 and between the second key recesses 146 and the second key portion 176, and the wears prevention member 180 that is inserted between the first key recess 166 and the first key portion 175 and between the first key recess 166 and the first key portion 175, which are described above, are the same in shape, but are opposite in the inward direction and the direction.

In addition, a shape of the wear preventing member 180 and a structure that prevents the wear preventing member 180 from being separated in the radial direction and the axial direction are also the same as those in the embodiments, which are described above. Therefore, the detailed descriptions of these are not repeated.

In FIGS. 21 and 22, reference character 147 denotes a radial direction separation prevention groove, reference character 148 an axial direction separation prevention groove, reference character 148 a a first axial direction separation groove, and reference character 148 b a second axial direction separation groove.

The scroll compressor according to the embodiment, as described above, has the following effects.

That is, the friction prevention member 180 are inserted between the first key recess 166 and the first key portion 175 and between the second key recesses 146 and the second key portion 176, respectively. Thus, the first key portion 175 of the Oldham ring 170 is prevented from being brought into direct contact with the first key recess 166 in the second scroll 160, and the second key portion 176 of the Oldham ring 170 is prevented from being brought into direct contact with the second key recesses 146 in the frame 140.

Accordingly, although the second scroll 160, the frame 140, and the Oldham ring 170 are all made of the same type of material, specifically, aluminum material that has a lower degree of hardness than cast iron, a decrease in friction characteristic between the Oldham ring 170 and the second scroll 160 and between the Oldham ring 170 and the frame 140 is suppressed, and the reliability of the compressor is improved.

In addition, the second scroll 160, the frame 140, and the Oldham ring 170 are all formed of light-weight aluminum material, and thus the weight of the compressor is reduced. This contributes to an increase in the efficiency of the compressor and of an apparatus that uses the compressor.

In addition, the ring portion 171 of the Oldham ring 170 and the key portions 175 and 176 are formed into a single body and thus connection parts of the ring portion and the key portion are sufficiently reinforced. Accordingly, the ring portion 171 and the key portions 175 and 176 are suppressed from being damaged due to application of force. This contributes to an increase in the reliability of the compressor.

In addition, the ring portion 171 of the Oldham ring 170 and the key portions 175 and 176 are formed into a single body, and thus a machining error between the ring portions 171 and the each of key portions 175 and 176 or deformation of the key portions 175 and 176 are minimized. Accordingly, the separation of the key portion from the key recess in a undesirable direction when driving the compressor is minimized and thus a compression loss due to a gap between wraps is suppressed.

In addition, a separate coating layer does not need to be formed on a surface of the Oldham ring 170. Thus the cost of manufacturing the Oldham ring 170 is reduced, and damage to the Oldham ring and a loss of frictional force thereof are suppressed.

On the other hand, in the embodiment described above, the radial direction separation prevention grooves 167 and 147 may form a type of oil storage space. Thus, while the compressor does not operate, as well as while the compressor operates, a fixed amount of oil can be stored. The stored oil flows between each of the key recesses 166 and 146 and each of the key portions 175 and 176, more precisely, between each of the key portions 175 and 176 and the wear preventing member 180 for lubrication. Thus, the wear of the key portions 175 and 176 can be suppressed more effectively. Therefore, a button surface of the radial direction separation prevention groove 167 may be formed to the same height as the bottom surface of the first key recess 166 that makes up the bottom surface 166 c.

However, as illustrated in FIG. 23, depending on the situation, the radial direction separation prevention groove 167 may be formed so that the bottom surface depth thereof is greater than the bottom surface depth of the first key recess 166. Accordingly, the oil storage groove 167 b is formed in the bottom surface of the radial separation prevention groove 167.

The oil storage groove 167 b, as described above, may be formed in the bottom surface of the radial direction separation prevention groove 167, but no limitation to the radial direction separation prevention groove 167 needs to be necessarily imposed. That is, the formation of the oil storage groove 167 b out of the range where the first key portion 175 moves is sufficient. For example, even if a separate radial direction separation prevention groove 167 is not formed, during the machining process, a groove in the shape of a semicircle may be formed in an end portion of the first key recess 166. The oil storage groove 167 b may be formed in this groove.

As described above, in a case where the oil storage groove 167 b is formed in the radial direction separation prevention groove 167, oil that is introduced into the first key recess 166 is stored in the oil storage groove 167 b. When the compressor operates, a fixed amount of oil is supplied between the first key recess 166 and the first key portion 175.

On the other hand, in the embodiment described above, the radial direction separation prevention portion 182 is formed in the shape of a circular arc, but a cross section of the radial direction separation prevention portion 182, as illustrated in FIG. 24, may be formed in the shape of a rectangle. In this case, it is desirable that the radial direction separation prevention groove 167 is also formed in the same shape as the radial direction separation prevention portion 182, that is, in the shape of a rectangle.

As described above, the radial direction separation prevention groove 167 and the radial direction separation prevention portion 182 are formed in the shape of a rectangle, and thus force in the radial direction that supports the wear preventing member 180 is increased much more. For this reason, the separation of the wear preventing member 180 can be suppressed more effectively.

In addition, on the other hand, a structure that securely holds a friction prevention member 180 according to another embodiment of the present disclosure is as follows.

That is, in the embodiments described above, the radial direction separation prevention grooves 167 and 147 are formed at positions, respectively, that communicate with the internal opening 166 f in the first and second key recesses 166 and 146, but in the present embodiment, the radial direction separation prevention groove 167 is formed on a border between the side walls, the side walls 166 a and 166 b, and the bottom surface 166 c of the first key recess 166. FIG. 25 is an exploded perspective diagram illustrating a radial direction separation prevention groove according to another embodiment of the present disclosure. FIG. 26 is a schematic diagram for describing an internal diameter of a key recess of FIG. 25.

As illustrated, in the present embodiment, the radial direction separation prevention groove 167 is not formed at an inner side of the first key recess 166, but is formed inside of the first key recess 166. Specifically, a first radial direction separation prevention groove 166 c 1 is formed on a border between the first side wall 166 a and the bottom surface 166 c of the first key recess 166. A second radial direction separation prevention groove 166 c 2 is formed on a border between the second side wall 166 b and the bottom surface 166 c of the first key groom 166. Then, a third radial direction separation prevention groove 166 c 3 is formed, in the shape of a circular arc, by extending from an internal end of the first radial direction separation prevention groove 166 c 1 to an internal end of the second radial direction separation prevention groove 166 c 2.

In the same manner as the first side wall 166 a and the second side wall 166 b, the first radial direction separation prevention groove 166 c 1 and the second radial direction separation prevention groove 166 c 2 are formed to be parallel to each other. An external end of the first radial direction separation prevention groove 166 c 1 and an external end of the second radial direction separation prevention groove 166 c 2 are formed to almost fit with external ends, respectively, of the first side wall 166 a and the second sidewall 166 b.

The third radial direction separation prevention groove 166 c 3 connects internal ends of the first radial direction separation prevention groove 166 c 1 and the second radial direction separation prevention groove 166 c 2 to each other. The third radial direction separation prevention groove 166 c 3 is formed to have a curved surface, and, depending on the situation, may be formed to have a straight-line surface.

At this point, the first radial direction separation prevention groove 166 c 1, the second radial direction separation prevention groove 166 c 2, and the third radial direction separation prevention groove 166 c 3 are formed to the same depth, and are formed to such a depth that one end in the axial direction, of the wear preventing member 180 is inserted and is supported in the radial direction.

As described, in a case where the radial direction separation prevention grooves 166 c 1 to 166 c 3 that prevent the wear preventing member 180 from being separated are not formed outside of the first key recess 166, and are instead formed inside of the first key recess 166, the separation of the wear preventing member 180 can also be effectively suppressed.

Furthermore, in this case, from the perspective of the second key recess 146, because the radial direction separation prevention groove is not formed outward with respect to the radial direction of the second key recesses 146, the second key recesses 146 can be moved outward by a radius of the radial direction separation prevention groove. Accordingly, the internal diameter of the ring portion 171 of the Oldham ring 170 can be increased and thus the internal diameter D1 of the backing space 144 can be increased. As a result, by increasing an area of the backing space 144, an area of the second scroll 160, on which backpressure is exerted, can be increased, and the behavior of the second scroll 160 can be stabilized.

In addition, the radial direction separation prevention portion 183 that has a structure which corresponds to the radial direction separation prevention grooves 166 c 1, 166 c 2, and 166 c 3 does not necessarily need to be sized larger than a semicircle. From FIGS. 25 and 26, it can be seen that a radius of a circle that corresponds to a circular arc of the radial direction separation prevention portion 183 is the same as a length in the circumferential direction between the first reinforcement plate 181 a and the second reinforcement plate 181 b.

In addition, on the other hand, a structure that securely holds a wear preventing member according to still another embodiment of the present disclosure is as follows.

That is, in the embodiments described above, the wear preventing member is securely held using the radial direction separation prevention groove that is provided in the vicinity of the key recess, and in the present embodiment, the wear preventing member is securely held using a separate fixation pin 185.

For example, as illustrated in FIGS. 27 and 28, the fixation pin 185 may be pressure-pushed inward from the radial direction separation prevention portion 183 of the wear preventing member 180, which is positioned at the deepest position in the first key recess 166, that is, positioned farthest from the center, and thus the radial direction separation prevention portion 183 of the wear preventing member 180 may be supported by the fixation pin 185 in the radial direction. The fixation pin 185 is inserted into a fixation groove and a fixation hole 166 c′ that is formed in the bottom surface 166 c of the first key recess 166.

In this case, a separate radial direction separation prevention groove also does not need to be formed in the vicinity of the first key recess 166, and the wear preventing member does not also need to be formed by enlarging the radial direction separation prevention portion 183. Therefore, in this case, the machining of the key recess and the manufacturing of the wear preventing member can also be facilitated.

Furthermore, in this case, as described above, from the perspective of the second key recess, a separate radial direction separation prevention groove also does not need to be formed. Because of this, the internal diameter of the Oldham ring can be increased. As a result, the behavior of the second scroll can be stabilized by increasing the area of the backing space.

In addition, on the other hand, a structure that securely holds a wear preventing member according to still another embodiment of the present disclosure is as follows.

That is, in the embodiments described above, the wear preventing member is provided only in both key recess surfaces of the key recess, but in the present embodiment, the wear preventing member is provided in not only the both key recess surfaces but also the bottom surface of the key recess. FIG. 29 is an exploded perspective diagram illustrating a wear preventing member according to another embodiment of the present disclosure. FIG. 30 is a plan-view diagram illustrating that the wear preventing member is assembled.

As illustrated, the wear preventing member 180 according to the present embodiment includes the first reinforcement plate 181 a, the second reinforcement plate 181 b, and a third reinforcement plate 181 c that is formed between the first reinforcement plate 181 a and the second reinforcement plate 181 b.

The first reinforcement plate 181 a and the second reinforcement plate 181 b are formed to be parallel to each other. The third reinforcement plate 181 c is formed as a result of bending and connection in the circumferential direction one end portion in the axial direction, of the first reinforcement plate 181 a and one portion in the axial direction, of the second reinforcement plate 181 b, which face each other, and serves to connect between the first reinforcement plate 181 a and the second reinforcement plate 181 b.

In addition, the third reinforcement plate 181 c corresponds to the bottom surface 166 c of the first key recess 166, and the third reinforcement plate 181 c is kept in close contact with the bottom surface 166 c of the first key recess 166. Accordingly, the wear preventing member 180 is formed to surround an entire internal surface of the first key recess 166 except for the opening 166 d in the axial direction, in the first key recess 166 that is opened.

At this point, radial direction separation prevention portions 184 a and 184 b are formed on the first reinforcement plate 181 a and the second reinforcement plate 181 b, respectively. The radial direction separation prevention portions 184 a and 184 b are formed as a result of bending the circumferential direction one end portion of the first reinforcement plate 181 a and one end portion of the second reinforcement plate 181 b, and serves to support the wear preventing member 180 in the radial direction.

The radial direction separation prevention portions 184 a and 184 b may be formed in the shape of a circular arc, in a manner that extends from a fixation end of the first reinforcement plate 181 a and a fixation end of the second reinforcement plate 181 b, respectively. Free ends of the two radial direction separation prevention portions, the radial direction separation prevention portions 84 a and 184 b, are at some distance away from each other.

In this case, the radial direction separation prevention groove 167 described above is formed inward with respect to the radial direction of the first key recess 166, and thus, the both radial direction separation prevention portions, the radial direction separation prevention portions 184 a and 184 b, are kept in close contact with an internal surface of the radial direction separation prevention groove 167.

Of course, in this case, a radial direction separation prevention groove (not illustrated) may also be formed in the bottom surface 166 c of the first key recess 166 so that the third reinforcement plate 181 c is inserted into the radial direction separation prevention groove. Furthermore, the first reinforcement plate 181 a and the second reinforcement plate 181 b may be elastically pressure-pushed into the first side wall 166 a and the second side wall 166 b, respectively, using the third reinforcement plate 181 c.

As described, in a case where the wear preventing member 180 is formed from the first reinforcement plate 181 a, the second reinforcement plate 181 b, and the third reinforcement plate 181 c, the wear preventing member 180 surrounds not only the first key surface 175 a and the second key surface 175 b of the first key portion 175, but also the third key surface 175 c that corresponds to the bottom surface 166 c of the first key recess 166. As a result, while the second scroll 160, which is an orbiting scroll, performs an orbiting motion, although an inclination phenomenon occurs, the bottom surface 166 c of the first key recess 166, and the third key surface 175 c of the first key portion 175 are suppressed from being brought into direct contact with each other.

Wear preventing members or key recesses according to still another embodiment will be described.

FIGS. 31 and 32 are exploded perspective diagrams, each illustrating the wear preventing member 180 and the key recess 166 according to the embodiment of the present disclosure.

An axial direction separation prevention groove 169 is formed as a result of recessing the bottom surface 166 c of the first key recess 166 along the radial direction of the rotation shaft 133. The axial direction separation prevention groove 169 extends up to an external opening in the first key recess 166 so that the wear preventing member 180 is inserted. A direction in which the axial direction separation prevention groove 169 is recessed is the axial direction of the rotation shaft 133, and the direction in which the axial direction separation prevention groove 169 extends is the radial direction of the rotation shaft 133.

The two side walls, the side walls 169 a and 169 b, of the axial direction separation prevention groove 169 are formed obliquely to be spaced more apart from each other as being away from the Oldham ring 170 (i.e., in a direction toward the first scroll).

The wear preventing member 180 includes the first reinforcement plate 181 a, the second reinforcement plate 181 b, and the third reinforcement plate 181 c. The first reinforcement plate 181 a and the second reinforcement plate 181 b extend in parallel to each other along the radial direction of the rotation shaft 133 from positions that are at some distance away from each other. Then, the third reinforcement plate 181 c is formed to connect the first reinforcement plate 181 a and the second reinforcement plate 181 b to each other and is kept in close contact with the bottom surface 166 c of the first key recess 166.

An axial direction separation prevention portion 186 is formed on the third reinforcement plate 181 c. The axial direction separation prevention portion 186 includes included two inclination surfaces, inclination surfaces 186 a and 186 b, and a connection surface 186 c. The two inclination surfaces, the inclination surfaces 186 a and 186 b, are formed so obliquely that they correspond to the both side walls 169 a and 169 b of the axial direction separation prevention groove 169, respectively. The two inclination surfaces, the inclination surfaces 186 a and 186 b, are formed so obliquely that they are spaced more apart from each other as being away from the Oldham ring 170 (in a direction toward the first scroll). The connection surface 186 c is formed to connect end portions of the two inclination surfaces, the inclination surfaces 186 a and 186 b, to each other.

When the axial direction separation prevention portion 186 is inserted into the axial direction separation prevention groove 169, with the inclination structure described above, the wear preventing member 180 can be prevented from being separated in the axial direction.

On the other hand, the radial direction separation prevention portions 184 a and 184 b include a first radial direction separation prevention portion 184 a and a second radial direction separation prevention portion 184 b, respectively, the first radial direction separation prevention portion 184 a is connected to one end of the first reinforcement plate 181 a. The second radial direction separation prevention portion 184 b is connected to one end of the second reinforcement plate 181 b.

The first radial direction separation prevention portion 184 a and the second radial direction separation prevention portion 184 b each include a fixation end and a free end. The fixation end refers to a part that is connected to one end of the first reinforcement plate 181 a or the second reinforcement plate 181 b. Then, the free end refers to a part that is formed in a direction opposite to a direction of the fixation end.

A free end of the first radial direction separation prevention portion 184 a and a free end of the second radial direction separation prevention portion 184 b are at some distance away from each other in FIGS. 31 and 32. The reason that the free end of the first radial direction separation prevention portion 184 a and the free end of the second radial direction separation prevention portion 184 b are at some distance away from each other is because the wear preventing member 180 is inserted into the first key recess 166.

In order to insert the wear preventing member 180 into the first key recess 166, pressure is applied to the first reinforcement plate 181 a and the second reinforcement plate 181 b of the wear preventing member 180 in a direction in which they approach each other. By application of pressure, the first reinforcement plate 181 a and the second reinforcement plate 181 b are inclined in the direction in which they approach each other with the third reinforcement plate 181 c in between. Then, the first radial direction separation prevention portion 184 a and the second radial direction separation prevention portion 184 b are inclined along the first reinforcement plate 181 a and the second reinforcement plate 181 b, respectively.

Before pressure is applied, a maximum distance in the circumferential direction of the rotation shaft 133 between the first radial direction separation prevention portion 184 a and the second radial direction separation prevention portion 184 b is longer than a distance between the first side wall 166 a and the second side wall 166 b of the first key recess 166. However, by application of pressure, when the maximum distance between the first radial direction separation prevention portion 184 a and the second radial direction separation prevention portion 184 b becomes shorter than the distance between the first side wall 166 a and the second side wall 166 b of the first key recess 166, the wear preventing member 180 can be inserted into the first key recess 166.

Pressure is applied until the maximum distance between the first radial direction separation prevention portion 184 a and the second radial direction separation prevention portion 184 b becomes shorter than the distance between the first side wall and the second side wall of the first key recess 166, and then the wear preventing member 180 is inserted into the first key recess 166. When the wear preventing member 180 is inserted into the first key recess 166, the axial direction separation prevention portion 186 is readily inserted into the axial direction separation prevention groove 169.

After the wear preventing member 180 is inserted into the first key recess 166, when the pressure is no longer applied, the first radial direction separation prevention portion 184 a and the second radial direction separation prevention portion 184 b return to their respective original positions and are kept in close contact with an inner circumferential surface of the radial direction separation prevention groove 167.

The maximum distance in the circumferential direction of the rotation shaft 133 between the first radial direction separation prevention portion 184 a and the second radial direction separation prevention portion 184 b is longer than a distance between the first reinforcement plate 181 a and the second reinforcement plate 181 b. Therefore, the wear preventing member 180 can be prevented from being separated in the radial direction.

The wear preventing member and the key recess, which are illustrated in FIG. 31, are the same as those, which are illustrated in FIG. 32, except for shapes of the radial direction separation prevention 184 a and 184 b and a shape of the radial direction separation prevention groove 167.

That is, in the wear preventing member and the key recess, which are illustrated in FIG. 31, the first radial direction separation prevention portion 184 a and the second radial direction separation prevention portion 184 b each are formed to have a curved surface with a cross section of a circular arc.

On the other hand, in the wear preventing member and the key recess, which are illustrated in FIG. 32, the first radial direction separation prevention portion 184 a and the second radial direction separation prevention portion 184 b extend from the first reinforcement plate 181 a and the second reinforcement plate 181 b, respectively, to be away from each other along the circumferential direction, and then are bent to be parallel to each other along the radial direction of the rotation shaft 133.

The radial direction separation prevention groove 167 has a shape that corresponds to the radial direction separation prevention portions 184 a and 184 b.

FIGS. 33 and 34 are exploded perspective diagrams, each illustrating a wear preventing member 180 and a key recess 166 according to another embodiment of the present disclosure.

The axial direction separation prevention portion 186 is formed in an inclined manner on a border between the first reinforcement plate 181 a and the third reinforcement plate 181 c and on a border between the second reinforcement plate 181 b and the third reinforcement plate 181 c. A first axial direction separation prevention portion 186 a is formed on a border between the first reinforcement plate 181 a and the third reinforcement plate 181 c. A second axial direction separation prevention portion 186 b is formed on a border between the second reinforcement plate 181 b and the third reinforcement plate 181 c. The first axial direction separation prevention portion 186 a and the second axial direction separation prevention portion 186 b are formed to be inclined in a direction in which they are spaced apart from each other.

The axial direction separation prevention groove 169 is formed by recessing both ends in the circumferential direction, of the bottom surface 166 c of the first key recess 166 in a manner of being inclined in a direction away from each other. The both ends in the circumferential direction, of the bottom surface 166 c of the first key recess 166 refers to a border between the first side wall 166 a and the bottom surface 166 c and a border between the second side wall 166 b and the bottom surface 166 c.

By application of pressure, the first reinforcement plate 181 a and the second reinforcement plate 181 b are caused to be inclined and the wear preventing member 180 is inserted in the radial direction into the first key recess 166. Then, when pressure is no longer applied, the wear preventing member 180 is held securely in the first key recess 166.

FIG. 35 is an exploded perspective diagram illustrating a wear preventing member 180 and a key recess 166 according to another embodiment of the present disclosure.

First radial direction separation prevention portions 187 a and 188 a and second radial direction separation prevention portions 187 b and 188 b are formed to extend from the first reinforcement plate 181 a and the second reinforcement plate 181 b, respectively, along the circumferential direction so as to be apart from each other.

The first radial direction separation prevention portions 187 a and 188 a are formed at both ends in the radial direction, respectively, of the first reinforcement plate 181 a. The second radial direction separation prevention portions 187 b and 188 b are formed at both ends in the radial direction, respectively, of the second reinforcement plate 181 b. The both ends of the first reinforcement plate 181 a or the second reinforcement plate 181 b refers to an external end and an external end.

By application of pressure, the first reinforcement plate 181 a and the second reinforcement plate 181 b are caused to be inclined and the wear preventing member 180 is inserted in the radial direction into the first key recess 166. Then, when pressure is no longer applied, the wear preventing member 180 is held securely in the first key recess 166.

FIG. 36 is an exploded perspective diagram illustrating a wear preventing member 180 and a key recess 166 according to another embodiment of the present disclosure.

The wear preventing member 180 includes the first reinforcement plate 181 a, the second reinforcement plate 181 b, and the third reinforcement plate 181 c.

The axial direction separation prevention portion 186 is configured as a fastening hole 181 c 1 that is formed in the third reinforcement plate 181 c. Then, an axial direction separation prevention groove 166 c′ is formed in a position that faces the fastening hole 181 c 1 in the axial direction.

With a fastening member 190 that passes through the fastening hole 181 c 1 and is fastened into an axial direction separation prevention groove 166 c′, the wear preventing member 180 is held securely in the first key recess 166. Example of the fastening member 190 include a bolt and a rivet. With the fastening member 190, the wear preventing member 180 can be presented for being separated both in the axial direction and in the radial direction.

In the above-described embodiments, although the example in which the Oldham ring is provided between the frame and the orbiting scroll and is slidably engaged with the frame and the second scroll has been described, but the Oldham ring may be slidably coupled to the key recess provided in the fixed scroll and the key recess provided in the orbiting scroll between the fixed scroll and the orbiting scroll.

Although the electric scroll compressor in which the casing is installed in the horizontal direction has been described in the above embodiments, the present disclosure may also be applied to a general scroll in which the casing is installed in a longitudinal direction.

In the above-described embodiments, the low-pressure type scroll compressor in which the internal space of the casing is formed as the suction space has been described. However, the present disclosure may be equally applied to a high-pressure type scroll compressor in which an internal space of the casing forms a discharge space. 

What is claimed is:
 1. A scroll compressor, comprising: a rotation shaft; a first scroll provided on one side of the rotation shaft; a second scroll engaged with the first scroll to form a compression chamber between the second scroll and the first scroll, the second scroll including a key recess in a surface disposed opposite to a surface facing the first scroll; an Oldham ring, including a ring portion and a key portion protruding from the ring portion toward the key recess, the key portion being configured to be slidingly coupled with the key recess such that the second scroll orbits with respect to the first scroll; and a wear preventing member installed between the key recess in the second scroll and the key portion of the Oldham ring, wherein the second scroll includes an axial direction separation prevention groove formed by recessing one surface of the key recess, and wherein the wear preventing member includes an axial direction separation prevention portion disposed in the axial direction separation prevention groove, the wear preventing member being held in place by an unrecessed portion of the one surface of the key recess.
 2. The scroll compressor of claim 1, wherein the Oldham ring is formed of the same material as the second scroll, and wherein the wear preventing member is formed of material that is different from that of at least one of the key recess in the second scroll or the key portion of the Oldham ring.
 3. The scroll compressor of claim 2, wherein the ring portion and the key portion are formed of the same material, and wherein the ring portion and the key portion form a single integral body.
 4. The scroll compressor of claim 1,wherein the wear preventing member further includes: first and second reinforcement plates that extend along a radial direction of the rotation shaft, the first and second reinforcement plates being positioned parallel to and spaced apart from each other, and radial direction separation prevention portions protruding from respective ends of the first reinforcement plate and the second reinforcement plate, the radial direction separation preventing portions being configured to prevent the wear preventing member from being separated from the key recess along the radial direction of the rotation shaft.
 5. The scroll compressor of claim 4, wherein the radial direction separation prevention portions are positioned closer to the rotation shaft than the first reinforcement plate or the second reinforcement plate.
 6. The scroll compressor of claim 4, wherein each of the first reinforcement plate and the second reinforcement plate extends from a fixation end connected to a respective radial direction separation prevention portion to a free end, and wherein the axial direction separation prevention portions are positioned adjacent the free ends of the first reinforcement plate and the free end of the second reinforcement plate, respectively, the axial direction separation prevention portions extending in a circumferential direction away from each other.
 7. The scroll compressor of claim 6, wherein the key recess in the second scroll further includes a first side wall configured to be in close contact with the first reinforcement plate, a second side wall spaced apart from the first side wall and configured to be kept in close contact with the second reinforcement plate, and a bottom surface connecting the first side wall and the second wall along a circumferential direction of the rotation shaft, the bottom surface facing the key portion, and wherein the axial direction separation prevention groove includes a pair of axial direction separation prevention grooves having a chamfer shape and extending between a convex outer surface of the second scroll and the first side wall, and between the convex outer surface of the second scroll and the second side wall.
 8. The scroll compressor of claim 6, wherein the axial direction separation prevention portion is formed by partially cutting the free ends of the first reinforcement plate and the second reinforcement plate in the radial direction of the rotation shaft.
 9. The scroll compressor of claim 6, wherein each of the free ends of the first reinforcement plate and the free end of the second reinforcement plate includes a first part that extends along a direction of extension of the first reinforcement plate and the second reinforcement plate, and a second part that extends from the first part to form the axial direction separation prevention portion, and wherein the second part is positioned closer to a bottom surface of the key recess than the first part.
 10. The scroll compressor of claim 9, wherein the key recess in the second scroll further includes a first side wall configured to be kept in close contact with the first reinforcement plate, a second side wall spaced apart from the first side wall and configured to be kept in close contact with the second reinforcement plate, and a bottom surface connecting the first side wall and the second wall to each other, the bottom surface facing the key portion, wherein each of the first side wall and the second side wall is divided into a first part that is relatively remote, along the axial direction of the rotation shaft, from the bottom surface of the key recess, and a second part that is relatively close to the bottom surface of the key recess, and wherein the axial direction separation prevention groove includes a pair of axial direction separation prevention grooves having a chamfer shape and extending between a convex outer surface of the second scroll and the second parts of the first side wall and the second side wall.
 11. The scroll compressor of claim 4, wherein the radial direction separation prevention portion is connected to one end of the first reinforcement plate and one end of the second reinforcement plate so as to have a curved surface with a cross section of a circular arc, wherein a diameter of a circle that corresponds to the circular arc is greater than a distance between the first reinforcement plate and the second reinforcement plate and wherein a magnitude of a central angle of the circular arc is greater than 90°.
 12. The scroll compressor of claim 11, wherein the key recess in the second scroll includes a radial direction separation prevention groove formed at a position relatively closer to the rotation shaft than the radial direction separation prevention groove or the key recess, and wherein the radial direction separation prevention groove has a circular segment that corresponds to the circular arc so as to accommodate the radial direction separation prevention portion.
 13. The scroll compressor of claim 4, wherein the axial direction separation prevention groove includes a recessed groove in the bottom surface of the key recess, the recessed grove extending along the radial direction of the rotation shaft, wherein the recessed groove includes two side walls spaced apart from each other and extending obliquely away from each other in an axial direction towards the first scroll, and wherein the axial direction separation prevention portion includes two inclination surfaces positioned obliquely to correspond to the two side walls of the axial direction separation prevention groove, respectively, and a connection surface that connects the two inclination surfaces to each other.
 14. The scroll compressor of claim 13, wherein the wear preventing member further includes a third reinforcement plate connecting the first reinforcement plate and the second reinforcement plate, the third reinforcement plate being configured to be positioned in close contact with the bottom surface of the key recess, and wherein the axial direction separation prevention portion is formed on the third reinforcement plate or wherein the two inclination surfaces of the axial direction separation prevention portion extend between the first and second reinforcement plates, respectively, and the third reinforcement plate.
 15. The scroll compressor of claim 13, wherein the radial direction separation prevention unit includes a first radial direction separation prevention portion connected to one end of the first reinforcement plate, and a second radial direction separation prevention portion connected to one end of the second reinforcement plate, wherein each of the first radial direction separation prevention portion and the second radial direction separation prevention portion extends from a fixation end connected to the one end of the first reinforcement or the one of the second reinforcement plate to a free end disposed opposite the respective fixation end, and wherein the free end of the first radial direction separation prevention portion is spaced apart from the free end of the second radial direction separation prevention portion.
 16. The scroll compressor of claim 15 wherein a maximum distance in a circumferential direction of the rotation shaft between the first radial direction separation prevention portion and the second radial direction separation prevention portion is longer than a distance between a first reinforcement plate and a second reinforcement plate.
 17. The scroll compressor of claim 15 where each of the first radial direction separation prevention portion and the second radial direction separation prevention portion includes a curved surface with a cross section of a circular arc.
 18. The scroll compressor of claim 15, wherein the first radial direction separation prevention portion includes a pair of first radial direction separation prevention portions extending from the first reinforcement plate along the circumferential direction of the rotation shaft, wherein the second radial direction separation prevention portion includes a pair of second radial direction separation prevention portions extending from the second reinforcement plate along the circumferential direction of the rotation shaft, wherein the pair of first radial direction separation prevention portions are respectively formed on both ends of the first reinforcement plate, and wherein the pair of second radial direction separation prevention portions are formed on both ends of the second reinforcement plate.
 19. The scroll compressor of claim 18, wherein the pair of first radial direction separation prevention portions are parallel to each other along the radial direction of the rotations shaft, and wherein the pair of second radial direction separation prevention portions are parallel to each other along the radial direction of the rotation shaft.
 20. The scroll compressor of claim 1, wherein the wear preventing member further includes: a first reinforcement plate and a second reinforcement plate that extend in parallel to each other along a radial direction of the rotation shaft, the first reinforcement plate being spaced apart from the second reinforcement plate; and a third reinforcement plate configured to be kept in close contact with the key recess, extending in a circumferential direction of the rotation shaft, and connecting the first reinforcement plate and the second reinforcement plate, wherein the axial direction separation prevention portion includes a fastening hole formed in the third reinforcement plate, wherein the axial direction separation prevention groove is formed in a position axially aligned with the fastening hole, and wherein, the wear preventing member is held securely in the key recess with a fastening member that passes through the fastening hole into the axial direction separation prevention groove. 